Fuse block and plug therefor



1 July 16, 1929 c. w. WALLIS 'FUSE BLOCK AND PLUG' THEREFOR [nzraniar LTZZLZZZTaZIzs Filed March 28, 1927 Patented July 16, 1929.

CHARLES WILLIAM WALLIS, OF TORONTO, ONTARIO, CANADA.

FUSE BLOCK AND PLUG THEREFOR.

Application filed March 28, 1927. Serial No. 179,139.

' My invention relates to improvements in fuse blocks and plugs therefor, and the object of the invention is to devise means for preventing the inserting of a fuse plug in a circuit carrying a heavier current than the circuit is capable of carrying, and also to provide means for preventing the easy closing of the circuit by the insertion of a metallic conductor such as a coin ina fuse plug orifice to bridge the contacts, and it consists essentially of the arrangement and construction of parts as hereinafter more particularly explained.

Fig. 1 is a sectional view through a fuse block and plug showing the plug partially inserted with the circuit open.

Fig. 2 isfa similar view to Figure 1 showing the fuse plug fully inserted so as to close the circuit.

In the drawing like characters of refer- I 'ence indicate corresponding parts in each figure.

1 indicates afuse block which is divided into two portions 1 and 1, the ortions 1" and 19 being-preferably formed 0 porcelain. The portion 1 is provided with an orifice 2 and the portion 1" with a recess 2 in alignment with the orifice 2. 3 is the centre contact of the block located centrally in the base of the recess 2". 4 is a metallic lining suitably s ecured in the orifice 2. 5 is a fuse plug provided with an outer metallic shell 6 and centre contact 7 The plug 5 is of usual construction and is therefore not described further in detail.

8 is a disc of insulating material such as fibre having a central orifice 8" correspond- I ing in diameter to the diameter of the centre contact 7 of the fuse plug 5. 9 is an upwardly convexed spring contact piece resting'at its edges upon the base of the recess 2 so as to cover the contact.3 and normally be spaced slightly therefrom so as to have no electricalconnection therewith. The disc 8 rests upon and covers the contact piece 9 as clearly shown in the drawing. 7

When the plug is screwed into position within the fuse block orifice the centre contact passes through the orifice 8* into contact withrthe contact piece9 depressing it into engagement with-the centre contact, 3 so as to form an electrical connection between the centre contact 3.and the centre contact 7 'when in the position shown in Figure 2. The

centre contact 7 of the fuse plugs is made any diameter in proportion to the strength of the current and to exactly fit the centre contact 7 of the fuse plug which it is adapted to carry.

The orifice 8 of the disc 8 corresponds in size to the size of the centre contact used.

It will, therefore be seen that should a person attempt to use a fuse plug having a larger contact 7 and unadapted to carry the strength of current of the circuit the centre contact thereof will be too large in diameter to pass throu h the centre orifice 8 of the disc 8 and there ore can not make contact with the centre contact 3 to close the circuit. When a fuse plug becomes burnt out very often the circuit is closed temporarily by the insertion of a coin or other metallic piece in the orifice of the fuse block so as to connect the centre described, the divided portions being secured together by means of screws 10.

It will therefore be seen that all that it is necessary to do when it is desired to render the block adaptable for other fuse plugs and circuits is to unscrew the screws 10 so as to separate the parts 1 and 1 and remove the disc and insert a new disc having an orifice of a diameter corresponding 'to the diameter of the centre contact of the new plug desired to be inserted in the block.

What I. claim as my invention is: The combination with a fuse block having a centre contact, a fuse plug having a centre contact opposing the contact of the block, a disc of insulating material inserted between thecontact of the block and the contact of the plug and having an orifice through which the centre contact of the plug must pass to engagewith the contact of the block, and -a spring convexed plate supporting the disc normally out of contact with the centre contact of the block.

CHARLES WILLIAM WALLIS. 

